Williams driver Felipe Massa has insisted that ruling Red Bull out of contention this season would be foolish.
The reigning world champions have experienced a few troubles in pre-season testing recently and do not find themselves amongst the quickest teams.
However, Massa believes that it is inevitable they will improve.
"We saw that Red Bull struggled every day, but the lap times they did [on Friday] were not so bad," Massa told Autosport.
"You can't put Red Bull and Lotus on the side because when they fix the problems we know that they have a good car, and we know they know how to make a winning car.
"It is always nice to say that a Red Bull is struggling but forget it. They have a problem to solve, but when it is solved they will be there."
Massa recently visited former teammate Michael Schumacher, who is still in hospital after a serious skiing accident at the end of last year.
Daniel Cross
